Surging at low speeds!!!

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Dec 11, 2006 | 08:37 PM

BNKBRKR

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From: SW KS

Surging at low speeds!!!

Hey guys, I was hoping someone can help me out here. I have a problem with the car in my sig. I bought the MS4 cam, and TSP mail order tune. I have LS1 Edit on the car and the tuning on it is great except for one thing. At low speeds (slowing down, off the gas, around 15mph and less) it wants to start surging. Now it seems to be speed related because as soon as it comes to a stop, it will instantly smooth out and idle great at 800rpm. I can tune at WOT but the driveability is throwing me a little bit and I don't want to just go in there tweaking things that should be left alone. Again the idle at a dead stop in park or in gear either one is great just slowing down ONLY 15mph or less. Thanks for any help guys!!! If you could tell me what to tweak, and how much to start with (and what it does) would be great!!!!

Dec 12, 2006 | 07:12 AM

pdanrichey

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From: Keller, TX

Probably a lack of nitrous at low speeds... Seriously, according to Paul Walker, N2O fixes everything!

j/k.

If it were an M6, I could understand it...but an auto doing that? Do you know what your AFR is? IMO, the problem that I've seen with the mail order tunes is that they do just tune for WOT, not your everyday driving circumstances. If they had you on a dyno tuning it, they could have tuned your drivability issue out...most likely.

So, are your RPMs also surging...or just the car? It could have something to do with your stall or the cam specs with the stall...?

Dec 12, 2006 | 08:28 AM

SSpdDmon

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From: Commerce Twp, MI

You need to watch your scanner while the surging is happening. It could be timing related, IAC related (throttle cracker/follower), or a little of both assuming your AFR is inline. That's the fundamental of tuning I think a lot of people miss. The tables are there in the PCM to the tell the engine components to do certain things. Finding the source of a problem is just like a trip to the doctor's office....process of elimination. The symptoms are your clues for where to look. Match the symptoms with the possible tables in the tuning software and scan the .pids associated with those tables.

Dec 12, 2006 | 09:03 AM

YellowToy/A

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From: Northern WV just south of MD

it is throttle cracker. Add some air where it is surging. Look at rpm and speed add air there. If you add to much air the car will stop slowing down. Adding air will open the IAC motor. Make sure your timing is not jumping.

Dec 12, 2006 | 04:40 PM

BNKBRKR

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From: SW KS

Timing does not seem to be jumping when surging. How much to add to the throttle cracker?

Dec 12, 2006 | 05:39 PM

SSpdDmon

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From: Commerce Twp, MI

Add a little at a time...like .25~.50 grams/second of airflow in the affected area.

Dec 12, 2006 | 06:12 PM

jimmyblue

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From: East Central Florida

It may not just be a matter of more air, but how the
airflow demand changes w/ road speed. I have seen
cracker tables (like mine stock) that have a big spike
in the low end. That kind of thing can make instability
as you bump across it or try to sit right where it's
most edgy. A soft landing is all that table is supposed
to produce.

https://ls1tech.com/forums/pcm-diagnostics-tuning/456413-weirdness-throttle-cracker-stalling-fix.html